JPH04229990A - Low power supply cable public hazard electric power control circuit - Google Patents

Abstract

PURPOSE: To provide a power control circuit with low power supply line pollution so that this technically simple circuit can be economically used in a small domestic electric apparatus. CONSTITUTION: This circuit has a control unit for regulating power consumption of a power semiconductor element, a switching element 30, loads 11 and 12, thereby exerting power control upon at least two ohmic loads 11 and 12 with low power line pollution. In order to prevent pollution caused by a power line in switching a high load, the control unit controls a power semiconductor unit 13 according to two switching directions, and either or both of the loads 11 and 12 are connected to the single power semiconductor 13 by way of the switching element 30. A simple and inexpensive circuit suitable for a small domestic electric apparatus such as a small cooking device, an iron and a cooking container is proposed in conformity with international standards.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a power semiconductor unit,
The present invention relates to a circuit for controlling low power line pollution power of at least two loads, including a switching element and a control unit for adjusting the power consumption of the loads.

0002

BACKGROUND OF THE INVENTION There are certain problems in the control and regulation of lamps, especially halogen lamps, which have very high starting and switching currents and very low cooling resistance. The reason for this is that lamp switching causes disturbances to the power supply line power source. Power control of such lamps with stepwise control of power consumption can be achieved by switching between mains power modes, such as parallel operation, series operation and off-state of two lamps, or by changing the mains power mode only for specific time intervals. It is known to turn on. When turning on a load, an undesired switching surge occurs, which causes associated power line voltage fluctuations.

The human eye is particularly sensitive to such power line voltage fluctuations in the frequency range around 10 Hz. For this reason, the IEC Standard 555
``Disturbance of the power supply system caused by household electrical appliances''
There are regulations regarding extremely small switching transients such as: In principle, this standard stipulates harmonics to 50Hz or higher and limits power line voltage fluctuations to 50Hz.
z or less to prevent undesired flicker from occurring. In particular, this means that power control with short switching times between line power modes is no longer possible for high loads, for example 1000W loads. The reason is that in this case the power line voltage fluctuations are no longer acceptable.

0004

This is why, for example, high-power lamps cannot be automatically set directly to full power in series or parallel operation. Furthermore, in order to reduce the power below the power of the supply voltage, it is necessary to lower the supply voltage, for example when operating the lamps in series. Also, although it is common practice to provide switched mode power supply, this is extremely complex and expensive. It is also conceivable to suppress individual phases of the supply voltage, but in this case too the power line voltage would be disturbed.

DE 37 26 535 A1 describes a method for power controlling electrical loads with a minimum of switching transients using a complex circuit using three triacs or six thyristors. For example, in the case of two loads, this circuit allows control in different switching modes, ie the two loads can be controlled individually, in parallel or in series. In this case, such circuits require complex and expensive electronic control equipment due to the large number of power semiconductor devices used and are prone to self-triggering, thus causing damage to the power semiconductor devices.

[0006] The switching state and the power line power supply half cycle pattern referred to herein mean the same thing as the switching mode. SUMMARY OF THE INVENTION It is an object of the present invention to provide a low power line pollution power control circuit which is technically simple and therefore economically usable in small domestic appliances such as small cookers, irons, cooking vessels and the like.

[0007]

SUMMARY OF THE INVENTION The present invention provides a circuit for controlling low power line pollution power of at least two loads, comprising a power semiconductor unit, a switching element, and a control unit for adjusting power consumption of loads. It is characterized in that the control unit controls the power semiconductor unit in two switching directions and connects one or two loads to a single power semiconductor unit via the switching element.

In a preferred embodiment of the present invention, the power semiconductor unit has a first terminal connected to a ground potential point and a second terminal connected to one load and connected to the other load via a switching element. To have a side.

[0009] In an advantageous embodiment of the invention, the power semiconductor unit comprises a triac or an anti-parallel connected thyristor, and the switching element comprises a single relay with a first and a second changeover switch.

In a preferred embodiment of the present invention, the first relay
In position the power semiconductor unit is connected to the phase terminal of the supply voltage via one load, the connection line, the second changeover switch and the other load, and in the second position of the relay the power semiconductor unit is connected to the one load and the first changeover switch. A switch is connected to the phase terminal of the supply voltage, such that the other load can be connected in parallel to the power semiconductor unit, the first load and the first changeover switch.

In a further preferred embodiment of the invention, a series arrangement comprising a semiconductor unit and two loads connected in parallel can be easily obtained by means of switching elements.

In a further preferred embodiment of the invention, the load is dependent on an electronic control unit by means of a switching element comprising a relay, making it possible to connect the loads in series and in parallel, and the power semiconductor unit is connected to the supply voltage source. and one of the loads and comprises one triac or two anti-parallel thyristors.

Advantageously, a thermistor is arranged in the connection line between the contacts of the relay switch to limit the turn-on transient. Furthermore, in a preferred embodiment of the invention, said control unit is configured as a logic device in the form of a microprocessor, and for the pollution-free control of the power consumption of said load, the circuit can be switched into various switching states: a) supply; voltage to operate two loads in parallel, b) supply voltage to operate only one load, c) supply voltage to operate only one load and the other load in 2/3, 1/3 or 1/ operate in 5-phase mode, d) operate as switching state c) with pulsed phase, e) operate two loads in series with the supply voltage, f) operate two loads in 2/3, 1
/3 or 1/5 phase mode; g) operating as switching state f) in pulsed phase;
h) Both loads are “switched off”, i
) causing one load to operate with the supply voltage and the other load to operate in 1/3 and 2/3 phase mode; j) both loads in 1/3 phase mode;
or operate in 1/3 phase mode.

[0014] The switching state b) and the associated phase mode are obtained by the associated turn-off of the power semiconductor unit. A sufficiently pollution-free turn-on can be obtained by the control unit sequentially generating the switching states f), e) and a). or,
The last-mentioned switching state can be replaced by a switching state i) or j) in which one load is connected to the supply voltage source and the other load is connected via the power semiconductor unit to the delay device. This allows currentless switching of the relay. This method of switching on has significant advantages compared to phase control methods. The reason is that it is simple and does not require expensive steps to suppress radio frequency interference.

The circuit according to the invention, which comprises only one relay and only one power semiconductor unit, is very simple in construction compared to conventional circuits and is capable of turning on, turning up and turning on, for example, two high-power lamps. Allows almost unimpeded turndown. In this case, the semiconductor unit protects the control unit from damage in the event of a failure. Minimum power can also be controlled through multiple possible switching states and pulse modes. Furthermore, the arrangement of the power semiconductor unit with respect to the ground point allows a simple DC-coupled control of the power semiconductor unit without the use of high-voltage transistors and protection diodes. Also, the linearly coupled zero point control signal from the control unit allows the power control unit to be reliably activated at the earliest possible instant without being affected by the load.

Furthermore, heat consumption can be reduced if the power semiconductor unit is arranged in series with only one load. There is also another advantage of arranging the loads in series via the operating contacts of the relay during control of the control unit, which is advantageous in the event of a fault. The reason is that the maximum possible power cannot be reached. It goes without saying that the changeover switches of the relays can also be individually switched to enable further switching modes.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. Figure 1
1 shows a power control circuit 10 of two ohmic loads 11, 12 according to the invention, which circuit has minimal power line pollution due to the power consumption of the loads 11, 12 and the loads are high power lamps. suitable. This circuit 10 comprises a power semiconductor unit 13 and a switching element 30 which is driven by a control unit and has two switching directions. switching element 30
Preferably, the relay 14 has a first changeover switch 15 and a second changeover switch 16.

In the operating position, the first changeover switch 15 initially connects the phase terminal 17 of the supply voltage source to the first load 11 arranged in series with the power semiconductor unit 13 . In the rest position of these switches 15 and 16, the second load 12 is connected via the associated rest contact of the second changeover switch 16 and the connection line 18 to the first load 11, which is connected to the power semiconductor unit on the output side. and connect this power semiconductor unit 13 to a ground point.

A control terminal 19 of the power semiconductor unit 13 receives a control signal, which is e.g.
1 and resistor 22 can be generated via terminal 20 from a logic device in the form of a microprocessor, for example. For this purpose, the base signal of the transistor 21 is made into a sawtooth wave signal. The relay 14 and thus the switching element 30 are also connected via the terminal 23 by a control unit, which may be a microprocessor and may also be another logic device.

In order to limit excessive turn-on transients, it is very advantageous to arrange a thermistor 24 in the connection line 18. The control unit is configured such that the circuit 10 can be set in different switching states for a pollution-free control of the power consumption of the loads 11 and 12. Depending on the position of the changeover switches 15 and 16 and on the control of the power semiconductor unit 13, the circuit enters the following advantageous switching states: a) With the supply voltage, the two loads 1
1, 12 are operated in parallel, b) only one load 12 is operated by the supply voltage, c) only one load 12 is operated by the supply voltage and the other load 11 is operated in parallel by 2/3, 1/3 or 1. /5 phase mode, d) switching state c in pulsed phase;
), e) operating the two loads 11,12 in series with the supply voltage, f) operating the two loads 11,12 in 2/3, 1/3 or 1/5 phase mode, g) Activated as switching state f) with pulsed phase, h) load 11,1
2 are both "switched off", i) energizing one load 12 with the supply voltage and the other 1;
1/3 of the load of 1 and 2/3 of the load 11 and 2/3 so that the operation in the phase mode is aligned, j) both loads 11, 12
can be switched to operate in 1/3 or 1/3 phase mode. State h) and the associated phase mode can be obtained by suitably turning off the power semiconductor unit 13, as explained below with respect to FIGS. 6, 7 and 8. Furthermore, the ground potential can be the potential of the neutral conductor of the three-phase feeder.

FIG. 2 shows a modification of the control circuit 10 of FIG. In this example, the operating contact 25 connected via the operating position of the second changeover switch 16 is not connected to a contact as shown in FIG. In the operating position of the switching contacts 15 and 16, a series arrangement of the power semiconductor unit 13 and the parallel-connected loads 11 and 12 can be obtained.

A particular advantage of this variant of the circuit is that current-free switching of the two loads 11 and 12 can be carried out during switching of the relay 14 from the rest position to the operating position and vice versa. be. Given the desired switching time and contact rebound of the relay 14, the relay 14 can be switched by the electronic control unit at zero crossings of the supply voltage and the current can be interrupted by the power semiconductor unit 13 for one to two half cycles. , this modified circuit allows relay 14 to be switched very economically, thus allowing the use of simple and inexpensive relays. However, according to such a modification, the power semiconductor unit 13
It is also necessary to consider that the heat dissipation will be higher. The reason for this is that when the loads 11 and 12 are operated in parallel, the entire current flows through the power semiconductor unit 13. The power semiconductor unit 13 of FIGS. 1 and 2 preferably comprises a triac 23. The power semiconductor unit 13 of FIGS.

3, 4 and 5 show the power semiconductor unit 13
2 illustrates various modifications of the circuit 10 shown in FIG. 1 in terms of type and arrangement. In particular, FIG. 3 shows a power semiconductor unit 13 comprising a triac 29, which in FIG. 1 was constituted by two anti-parallel thyristors 27, so that again two switching directions are possible.

FIG. 4 shows the power semiconductor unit 13 divided into two parts. Each of these two parts comprises a thyristor 27 and a diode 28 antiparallel to it, switching in one switching direction and arranged in series with one load 11 or the other load 12. The advantage of this modification is that the semiconductor device cannot be destroyed by self-triggering.

FIG. 5 shows another modification of the circuit 10 shown in FIG.
The triac is arranged between the terminal 17 and the load 12. Due to the dependable triggering of the semiconductor components of the power semiconductor unit 13, the triggering in all variants of the control circuit according to the invention occurs at the earliest possible instant, without being influenced by the DC-coupled zero point control signal on the loads 11 and 12. can be done. Furthermore, since the trigger voltage of the semiconductor component is dependent on the load, the trigger pulse will shift in the case of short trigger pulses that can be applied by control. Therefore, the relatively slow, especially DC isolated triggering causes interference to the radio and requires additional structural improvements.

FIG. 6 shows 1 plotted along the time axis t.
/3 Shows the basic voltage waveform in phase mode. That is,
Each valid half-cycle, shown in solid lines, is followed by two invalid half-cycles, shown in dashed lines. Similarly, a 1/5 phase mode (not shown) can be obtained.

FIG. 7 shows the pulsed voltage waveform U associated with the 1/3 phase mode of FIG. 6, but with the time axis t plotted on a different scale. With a turn-on pulse width of, for example, greater than or equal to 300 ms and a turn-off pulse width of a few tens of ms to a few seconds, for example two halogen lamps can be powered with 1000 W each according to the above-mentioned IEC 555 standard.

FIG. 8 shows the fundamental voltage waveform U in the 2/3 phase mode plotted on the time axis t, similar to FIG. In this case, two valid half-cycles, shown in solid lines, are followed by one invalid half-cycle, shown in broken lines. Figure 9 shows the time t for the soft start/turn-up cycle from zero power to the maximum power that generally produces the least pollution of the supply voltage.
Power consumption is shown on the vertical axis as a function of .

Switching state h) corresponds to zero power and switching state a) corresponds to maximum power. The turn-on time for each switching state is 120 ms for switching state f) and each time for one half cycle switching to 1/3 phase mode and 2/3 phase mode is 180 ms for switching state e)
ms. For example, two loads 11 and 12 are 100
Following switching state a), which supplies power at 0 W, each load becomes different for the two variants of the circuit of FIGS. 1 and 2.

In FIG. 1, the relay 14 is approximately 20 ms
and switching state b) is
Only the load 12 will predominate for the other 60ms connected to the supply voltage source. Switching state c) then requires 120 ms for each half-cycle time in the 1/3 and 2/3 phase modes in addition to the load 11.

In FIG. 2, the relay 14 initially switches over within approximately 20 ms and the power semiconductor unit 1
Turn off 3. Then, to achieve a soft transient, the two loads 11, 12 are switched in the switching state j), i.e. 1/3 phase mode for 30 ms and the other 30 m
s operates in parallel in 2/3 phase mode.

Other power states, for example switching states c) and d) with power between maximum power and half power.
, or approximately 5% of the maximum power by arbitrarily selecting the pulse ratio
The power states corresponding respectively to the switching state g) with a minimum power of 15% can be used as the warming state of the heating device.

Other advantageous start-up/turn-up cycles (
(not shown) are switching states f), e) and a)
can be obtained by sequentially using Alternatively, the last mentioned switching state a) can be replaced by switching state i) or j).

Compared to the phase control method, the start-up cycle described in the present invention does not require expensive measures to suppress radio frequency interference and is soft enough to significantly reduce power line pollution. The present invention is not limited to the above-described examples, and various modifications and changes can be made without departing from the gist.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the configuration of a control circuit of the present invention in which two loads are directly connected, only one load is operated, and the other load can be added in any switching mode.

2 is a circuit diagram showing a variant of FIG. 1 in which two loads can be arranged in series and in parallel in any switching mode; FIG.

3 shows a circuit diagram similar to the circuit of FIG. 1 with a modified power semiconductor unit; FIG.

4 shows a circuit diagram similar to FIG. 1 with a divided and modified power semiconductor unit; FIG.

5 shows a circuit diagram similar to FIG. 1 with a power semiconductor unit between a supply voltage source and a load; FIG.

FIG. 6 is a characteristic diagram showing a fundamental voltage waveform in 1/3 phase mode.

FIG. 7 is a characteristic diagram showing a basic voltage waveform in pulsed 1/3 mode.

FIG. 8 is a characteristic diagram showing a fundamental voltage waveform in 2/3 phase mode.

[Figure 9] Start-up to maximum power cycle with minimum power line pollution/
It is an explanatory view showing switching diagrammatically.

[Explanation of symbols]

10 Low power line pollution power control circuit 11, 12 Load 13 Power semiconductor unit 14 Relay 15 First changeover switch 16 Second selector switch 17 Terminal 18 Connection line 19 Control terminal 20 Terminal 22 Resistance 23 Terminal 24 Thermistor 25 Operation contact 27 Thyristor 28 Anti-parallel diode 29 Triac 30 Switching element

Claims (10)

[Claims] 1. A circuit for controlling low power line pollution power of at least two loads, comprising a power semiconductor unit, a switching element, and a control unit that adjusts power consumption of loads, wherein the control unit controls two switching elements. It is characterized in that the power semiconductor unit (13) is controlled with respect to the direction, and one or two loads (11, 12) are connected to the single power semiconductor unit (13) via the switching element (30). Low power line pollution power control circuit. 2. The power semiconductor unit (13) has a first terminal connected to a ground potential point and one load (11).
) and a second terminal side connected to the other load (12) via the switching element (30). 3. The power semiconductor unit (13) comprises 1
two triacs (29) or anti-parallel connected thyristors (
27), and the switching element (30) comprises a single relay (14) with a first and a second changeover switch (15, 16). Power control circuit. 4. In the first position of the relay (14), the power semiconductor unit (13) switches one load (11), the connection line (18), the second changeover switch (16) and the other load (12). In the second position of said relay (14), the power semiconductor unit (13) connects to the phase terminal (17) of the supply voltage via one load (11) and the first changeover switch (15). 4. The phase terminal (17) is connected to the other load (12), and the other load (12) is connected in parallel to the power semiconductor unit, the first load, and the first changeover switch. Low power line pollution power control circuit. 5. In the first position of the relay (14),
The power semiconductor unit (13) is one of the loads (11)
, connection line (18), second second changeover switch (16)
and the phase terminal (1) of the supply voltage via the other load (12)
7), and in the other position of said relay (14) the power semiconductor unit (13) is connected to said phase terminal (17) of the supply voltage via one load (11) and a first changeover switch (15). The other load (12) is connected in parallel to the first load (11) and the first changeover switch via a second changeover switch (16) and a connection line (26). The low power line pollution power control circuit according to claim 3. [Claim 6] The two changeover switches (15, 16
) The relay (14) has a switching element (30
) and connect the loads (11, 12) in series or parallel depending on the control unit, and the power semiconductor units (1
3) is associated with each of the loads (11, 12), and when the two loads (11, 12) are operated in parallel, the relevant part of the power semiconductor unit (13) has a first terminal connected to the ground potential point. 2. A low line pollution power control circuit according to claim 1, characterized in that it has an antiparallel connected diode (28) and a thyristor (27). [Claim 7] The two changeover switches (15, 16
) The relay (14) has a switching element (30
) and, depending on the control unit, connect the loads (11, 12) in series or in parallel, and the power semiconductor unit (13) connects the phase terminals (17) of the supply voltage.
one triac (29) or two anti-parallel connected thyristors (27) with a first terminal side connected to
The low power line pollution power control circuit according to claim 1, further comprising: a low power line pollution power control circuit; 8. A thermistor (24) is arranged in the connection line (18) between the actuation contact of the first changeover switch (15) and the remaining contacts of the second changeover switch to limit turn-on transients. The low power line pollution power control circuit according to any one of claims 1 to 7. 9. The control unit is configured as a logic device in the form of a microprocessor and is configured to control the load (1).
1, 12) for controlling power consumption without pseudo-pollution.
The following switching states: a) the supply voltage operates two loads (11, 12) in parallel, b) the supply voltage operates only one load (11), c)
operating only one load (12) with the supply voltage and operating the other load (11) in 2/3, 1/3 or 1/5 phase mode, d) operating as switching state c) in pulsed phase; let, e)
The supply voltage operates two loads (11, 12) in series, f) two loads (11, 12)
3, operating in 1/3 or 1/5 phase mode;
g) operating in the switching state f) in a pulsed phase; h) placing both loads (11, 12) in the "switched off"state; i) operating one load (12) with the supply voltage and the other Load (11)
j) both loads (11, 12) are operated in 1/3 or 1/3 phase mode; The low power line pollution power control circuit according to any one of claims 1 to 8. [Claim 10] In the start/turn-on cycle,
Switching states f), e) and a), i) or j) are activated in sequence to obtain maximum power, and at least one of switching states b) to j) is transitioned to reduce power consumption. The low power line pollution power control circuit according to any one of claims 1 to 9.